1. Field of the Invention
This invention relates to self-priming centrifugal pumps which are used to process fluids that usually contain solids. Specifically, this invention relates to providing an improved check valve system for self-priming pumps that facilitates maintenance and repair of the check valve of the pump.
2. Description of Related Art
Self-priming centrifugal pumps are well-known and frequently used in industries where processing fluids with entrained solids is required. Self-primer pumps, also known as trash pumps, are characterized as having a casing which houses a suction chamber and a separation chamber divided by a wall or plenum. An impeller positioned in a volute section of the pump receives fluid from the suction chamber and delivers it by centrifugal action into the separation chamber where it is eventually expelled through an outlet.
Self-primer pumps are further structured with a check valve that is positioned at or adjacent the inlet to the pump. In operation, as fluid enters through the inlet, the check valve remains open, allowing fluid to enter into the suction chamber of the pump. When the pump stops, the check valve will seat against the inlet opening to prevent fluid from leaving the suction chamber of the pump. That is, if the check valve remains open or does not seat properly against the inlet, fluid is siphoned back out of the suction chamber until the siphoning action, or siphon leg, is broken. As a result, the fluid level in the suction chamber is very low making re-priming of the pump very difficult. It is desirable, therefore, to assure that fluid remains in the suction chamber.
In known self-primer pumps, small sized pumps are provided with a flapper-type check valve that incorporates a fabric-type hinge that is molded into the valve. In larger sized pumps, a flapper valve is employed having a metallic hinge because more stresses are placed on the valve, thereby making a fabric-type hinge impractical and too subject to failure. In both types of check valves in known conventional pumps, the means by which the valve is secured to the pump casing or inlet make it very difficult to service the check valve for maintenance or repair. Oftentimes, the check valve or hardware used to secure the check valve to the pump casing or inlet opening is dropped into the interior of the pump, which can be detrimental to pump operation and repair.
It would be advantageous in the art, therefore, to provide a check valve assembly that is easy to secure to the pump casing and is easily accessible for servicing the check valve in maintenance or repair without losing the valve or hardware in the pump.